Diesel Shed summer training report at NR Diesel Shed, Kalka

1. 1
INDIAN RAILWAY HISTORY
Indian Railways is the state-owned railway company of India. It comes under the Ministry of
Railways. Indian Railways has one of the largest and busiest rail networks in the world,
transporting over 18 million passengers and more than 2 million tonnes of freight daily. Its
revenue is Rs.107.66 billion. It is the world's largest commercial employer, with more than
1.4 million employees. It operates rail transport on 6,909 stations over a total route length of
more than 63,327 kilometres (39,350 miles). The fleet of Indian railway includes over
200,000 (freight) wagons, 50,000 coaches and 8,000 locomotives. It also owns locomotive
and coach production facilities. It was founded in 1853 under the East India Company.
Indian Railways is administered by the Railway Board. Indian Railways is divided into 16
zones. Each zone railway is made up of a certain number of divisions. There are a total of
sixty-seven divisions. It also operates the Kolkata metro. There are six manufacturing plants
of the Indian Railways. The total length of track used by Indian Railways is about
108,805 km (67,608 mi) while the total route length of the network is 63,465 km (39,435 mi).
About 40% of the total track kilometres is electrified & almost all electrified sections use
25,000 V AC. Indian railways uses four rail track gauges:
1. The broad gauge (1670 mm)
2. The meter gauge (1000 mm)
3. Narrow gauge (762 mm)
4. Narrow gauge (610 mm).
Indian Railways operates about 9,000 passenger trains and transports 18 million passengers
daily. Indian Railways makes 70% of its revenues and most of its profits from the freight
sector, and uses these profits to cross-subsidies the loss-making passenger sector. The
Rajdhani Express and Shatabdi Express are the fastest trains of India
CLASSIFICATION:
1. Standard “Gauge” designations and dimensions:
 W = Broad gauge (1.67 m)
 Y = Medium gauge (1 m)
 Z = Narrow gauge (0.762 m)
 N = Narrow gauge (0.610 m)

2. 2
2. “Type of Traction” designations:
 D = Diesel-electric traction
 C = DC traction
 A = AC traction
 CA=Dual power AC/DC traction
3. The “Type of load” or “Service” designations:
 M= Mixed service
 P = Passenger
 G= Goods
 S = Shunting
4. “ Horse power ” designations from June 2002 (except WDP-1 & WDM-2 LOCOS)
 ‘ 3 ’ For 3000 horsepower
 ‘ 4 ’ For 4000 horsepower
 ‘ 5 ’ For 5000 horsepower
 ‘ A ’ For extra 100 horsepower
 ‘B’ For extra 200 horsepower and so on.
Hence ‘WDM-3A’ indicates a broad gauge loco with diesel-electric traction. It is for mixed
services and has 3100 horsepower.|~|

3. 3
CHAPTER-1
INTRODUCTIONOF THE DIESELSHED
Diesel locomotive shed is an industrial-technical setup, where repair and maintenance works
of diesel locomotives is carried out, so as to keep the loco working properly. It contributes to
increase the operational life of diesel locomotives and tries to minimize the line failures. The
technical manpower of a shed also increases the efficiency of the loco and remedies the
failures of loco.
The shed consists of the infrastructure to berth, dismantle, repair and test the loco and
subsystems. The shed working is heavily based on the manual methods of doing the
maintenance job and very less automation processes are used in sheds, especially in India.
The diesel shed usually has:
 Berths and platforms for loco maintenance.
 Pits for under frame maintenance
 Heavy lift cranes and lifting jacks
 Fuel storage and lube oil storage, water treatment plant and testing labs etc.
 Sub-assembly overhauling and repairing sections
 Machine shop and welding facilities.
ABOUT DIESEL SHED KALKA
Diesel Shed, Kalka of Northern Railway is located in Indian State of Haryana. The shed was
established in 1891. It was initially planned to home 75 locomotives. The shed cater the
needs of Northern railway. This shed mainly provides locomotive to run the mail, goods and
passenger services. No doubt the reliability, safety through preventive and predictive
maintenance is high priority of the shed. The Diesel Shed is equipped with modern machines
and plant required for Maintenance of Diesel Locomotives and has an attached store depot.
To provide pollution free atmosphere, Diesel Shed has constructed Effluent Treatment Plant.
The morale of supervisors and staff of the shed is very high and whole shed works like a
well-knit team.

4. 4
1.1 SPECIAL MACHINES & PLANT
Pit wheel lathe machine
This machine is suitable for turn & re-profiles the wheels of locomotives.
Effluent Treatment Plant
In order to provide pollution free environment, an ETP PLANT is installed. Various effluents
emitted from diesel shed are passed through the Plant. The water thus collected is pollution
free and is used for non drinking purposes such as gardening and washing of the locomotives.
1.2 FUEL SECTION
Figure 1.1 Fuel section
The section is concern with receiving, storage and refilling of diesel and lube oil. It has 3
large storage tanks and one underground tank for diesel storage which have a
combined storage capacity of 10,60, 000 litters. This stock is enough to end for 15-16 days.
The fuel is supplied by truck from IOCL - Panipat refinery each truck diesel sample
is treated in diesel lab and after it in unloaded. Sample check is necessary to avoid

5. 5
water, kerosene mixing diesel. Two fuel filling points are established near the control
room It also handles the Cardiam compound , lube oil. Diesel is only for loco use if the
diesel samples are not according to the standard , the delivery of the fuel is rejected.
Viscosity of lube oil should be 100-1435 CST. Water mixing reduces the viscosity.
Statement of diesel storage and received is made after every 10 days and the report is send to
the Division headquarter. The record of each truck, wagons etc are included in it. The record
of issued oil is also sending to headquarter. After each 4 months. A survey is conducted by
high level team about the storage, records etc. 0.1% of total stored fuel oil is given for
handling losses by the HQ. The test reports of diesel includes the type of diesel (high speed
diesel- Euro-3 with 0.035 % S), reason for test, inspection lot no, store tank no, batch no. etc.
1.3 CONTROL ROOM
It controls and regulates the complete movement, schedules, duty of each loco of the shed.
Division level communications and contacts with each loco on the line are also handled by
the control room. Full record of loco fleet, failures, duty, overdue and availability of locos are
kept by the control room. It applies the outage target of loco for the shed, as decided by the
HQ. It decides the locomotives mail and goods link that which loco will be deployed on
which train.
The schedule of duty, trains and link is decided by the control room according to the type of
trains. If the loco does not return on scheduled time in the shed then the loco is termed as ‘
over due’ and control room can use the loco of another shed if that is available.
The lube oil consumption is also calculated by the control room for each loco:-
Lube Oil Consumption (LOC) = Lube oil consumed in liters/ total kms travelled ×100
New and better operational loco have less LOC.
1.4 CTA (Chief Technical Assistance) CELL
This cell performs the following functions
 Failure analysis of diesel locos
 Finding the causes of sub system failures and material failures

6. 6
 Formation of inquiry panels of Mechanical and Electrical engineers and to help the
special inquiry teams
 Material failures complains, warnings and replacement of stock communications with the
component manufacturers
 Issues the preventive instructions to the technical workers and engineers
 Preparation of full detailed failure reports of each loco and sub systems, components after
detailed analysis. The reports are then sent to the Divisional HQ.
 Correspondence with the headquarters is also done by the CTA Cell.

7. 7
CHAPTER-2
DIESELENGINE
This is the type of internal combustion engine in which air is compressed and due to
compression the temperature of air is raised to the considerable amount and at the end when
the air becomes too much hot the diesel oil is injected into the cylinder in the shape of spray.
now these small particles of oil when comes into the contact of hot air, starts burning. this
diesel engine is also called compression ignition engine and this type in the cylinder. after
that the power is developed and these functions are: Suction, compression, power, exhaust.
The combination of above four is called one cylinder some of the engine completes all the
cycle in two stroke and some in four strokes and accordingly it is called two stroke and four
stroke engine.
CYCLE: The compilation of all these four functions i.e. suction, compression,
power, and exhaust in a specific sequences are called one cycle.
STROKE: The movement of piston from TDC to BDC or from BDC to TDC is called
Stroke.
TDC: The upper position of the piston from which the piston starts move downward is called
'TDC'. (Top Dead Center).
BDC: The bottom position of the piston from which the piston starts move upward is called
'BDC'. (Bottom Dead Centre).
COMPRESSION RATIO: The compression ratio of IC engines is the ratio of between
clearance volume and total volume i.e. clearance volume + swept volume. In other words,
this ratio is indicative of the degree of compression of trapped air. Higher the compression
ratio, higher will be the compression pressure and consequently higher the temp. It is for this
reason that compression ratio of spark ignition engine is lesser (round about 8:1) whereas the
compression ratio of compression ignition is 12:5:1 and above.
Compression ratio = VS + VC/ VC
WDM-2 loco's compression ratio= 12:5:1 and firing order from right to left is 14 76 85 23.

8. 8
2.1 DIESEL ENGINE MAIN PARTS
In this section the attempt has been made to give in brief the essential details in respect of
design, construction , working of the diesel engine components. the discussion has been kept
confined to standard locos of Indian railways . example- WDM-2, WDS4,and ZDM3. In
some cases the examples of typical components of non-standard locos have been touched
upon where considered necessary material specification and critical dimensions have been
quoted to the extent possible to make the content more useful.
The diesel engine consists of following major components and assemblies:
a. engine base.
b. engine block
c. crank shaft
d. cam shaft
e. cylinder head
f. valves
g. piston
h. piston rings
i. cylinder liner
j. connecting rod
k. main and connecting rod bearing
l. exhaust manifold.
We will discuss above 5 topics one by one:
2.1.1 ENGINE BASE: The engine base of ALCO LOCOS WDM-2, WDS-4 are made from
wieldable quality steel to specification is -2062 with 0.2% of carbon. The engine base of
ALCO LOCOS have following functions, it has to
(a) support the engine block
(b) serve as oil pump.
(c) accommodate lube oil main header.
(d) take lube oil pump and water pump at the free end.
(e) allow opening for crank case inspection
(f) take filament of crank case explosion cover.

9. 9
(g) foundation pads are provided for transmitting load to the chassis and also to take lower
bolts of the main generator magnet frame.
Figure 2.1 Engine block
2.1.2 ENGINE BLOCK: The engine block is the most important and very highly stressed
structure on which are fitted a number of important fillings like crank shaft , cylinder heads,
cylinder liners, piston con rods, fuel injection pumps and cross head, turbo support, governor
etc. Like engine base this structure (in case of ALCO LOCOS is also fabricated from low
carbon steel).
2.1.3 CRANK SHAFT: The engine crankshaft is probably the singular costlier item in the
diesel engine. it is the medium of transforming reciprocating motion to rotary motion. the
crank shaft may be assembled type or two piece bolted type or may be single welded. the
standard locos of Indian railways are with single MAK/CLW engines the counter weights are
bolted. The ALCO crankshafts manufactured from chrome-molybdenum steel.

10. 10
2.1.4 CAM SHAFT: In diesel engine the cam shaft performs the vital role of opening and
closing inlet and exhaust valves and alloying timely injection of fuel inside the cylinder.
Figure 2.2 Crank shaft
Usual practice to provide 3 cams for each cylinder the two outer cams being for exhaust and
inlet valves and the central cam being for fuel injection. Like most of the diesel engines
manufactures ALCO engines have cams integral with cam shaft each cam shaft section takes
care of two cylinders.

11. 11
Figure 2.3 Cam Shaft
2.1.5 CYLINDER HEADS: The cylinder head is held on to the cylinder liner by several
hold down studs or bolts provided on the cylinder block. It is subjected to high shocks.

12. 12
CHAPTER-3
ENGINE ACCESSORIES
3.1 TURBO SUPERCHARGER
3.1.1 Introduction
The diesel engine produces mechanical energy by converting heat energy derived from
burning of fuel inside the cylinder. For efficient burning of fuel, availability of sufficient
air in proper ratio is a prerequisite.
In a naturally aspirated engine, during the suction stroke, air is being sucked into the cylinder
from the atmosphere. The volume of air thus drawn into the cylinder through restricted inlet
valve passage, within a limited time would also be limited and at a pressure slightly less than
the atmosphere. The availability of less quantity of air of low density inside the cylinder
would limit the scope of burning of fuel. Hence mechanical power produced in the cylinder is
also limited.
An improvement in the naturally aspirated engines is the super-charged or pressure charged
engines. During the suction stroke, pressurised stroke of high density is being charged into
the cylinder through the open suction valve. Air of higher density containing more oxygen
will make it possible to inject more fuel into the same size of cylinders and produce more
power, by effectively burning it.
A turbocharger, or turbo, is a gas compresser used for forced-induction of an internal
combustion engine. Like a supercharger, the purpose of a turbocharger is to increase the
density of air entering the engine to create more power. However, a turbocharger differs in
that the compressor is powered by a turbine driven by the engine's own exhaust gases.
Figure 3.1 Turbocharger

13. 13
3.1.2 Turbo supercharger and its working principle
The exhaust gas discharge from all the cylinders accumulate in the common exhaust manifold
at the end of which, turbo- supercharger is fitted. The gas under pressure there after enters the
turbo- supercharger through the torpedo shaped bell mouth connector and then passes
through the fixed nozzle ring. Then it is directed on the turbine blades at increased pressure
and at the most suitable angle to achieve rotary motion of the turbine at maximum efficiency.
After rotating the turbine, the exhaust gas goes out to the atmosphere through the exhaust
chimney. The turbine has a centrifugal blower mounted at the other end of the same shaft and
the rotation of the turbine drives the blower at the same speed. The blower connected to the
atmosphere through a set of oil bath filters, sucks air from atmosphere, and delivers at higher
velocity. The air then passes through the diffuser inside the turbo- supercharger, where the
velocity is diffused to increase the pressure of air before it is delivered from the turbo-
supercharger.
Pressurising air increases its density, but due to compression heat develops. It causes
expansion and reduces the density. This effects supply of high-density air to the engine. To
take care of this, air is passed through a heat exchanger known as after cooler. The after
cooler is a radiator, where cooling water of lower temperature is circulated through the tubes
and around the tubes air passes. The heat in the air is thus transferred to the cooling water and
air regains its lost density. From the after cooler air goes to a common inlet manifold
connected to each cylinder head. In the suction stroke as soon as the inlet valve opens the
booster air of higher pressure density rushes into the cylinder completing the process of super
charging.
The engine initially starts as naturally aspirated engine. With the increased quantity of fuel
injection increases the exhaust gas pressure on the turbine. Thus the self-adjusting system
maintains a proper air and fuel ratio under all speed and load conditions of the engine on its
own. The maximum rotational speed of the turbine is 18000/22000 rpm for the Turbo
supercharger and creates max. Of 1.8 kg/cm2 air pressure in air manifold of diesel engine,
known as Booster Air Pressure (BAP). Low booster pressure causes black smoke due to
incomplete combustion of fuel. High exhaust gas temperature due to after burning of fuel
may result in considerable damage to the turbo supercharger and other component in the
engine.

14. 14
3.1.3 Main components of turbo-supercharger
Turbo- supercharger consists of following main components.
 Gas inlet casing.
 Turbine casing.
 Intermediate casing
 Blower casing with diffuser
 Rotor assembly with turbine and rotor on the same shaft.
3.1.4 Rotor assembly
Figure 3.2 Impeller and rotor assembly
The rotor assembly consists of rotor shaft, rotor blades, thrust collar, impeller, inducer, centre
studs, nosepiece, locknut etc. assembled together. The rotor blades are fitted into fir tree slots,
and locked by tab lock washers. This is a dynamically balanced component, as this has a very
high rotational speed.
3.2 GOVERNOR
It is located on engine right side on power take off end. its main work to keep the engine
RPM stable as per throttle notch position irrespective of load and position.....
3.2.1 Working of governor:
(1) constant the rpm according to the throttle notch.
(2) to balanced the HP + load between main generator and engine.
(3) fuel controls of fuel oil supply.
(4) when any safety device operated that time, engine will come in idle position on shut
down.
(5) help the engine bore starting or stopping.

15. 15
Figure 3.3 Electronic governors
3.2.2 Types of governor:
a. Electro hydraulic governor (EH)
b. Woodwork governor(WW)
c. Microprocessor control based governor (MCBG)
3.3 TURBO SUPER CHARGER
3.3.1 Super charging: The process of pressurized air more than atmospheric pressure
supplied to the cylinder for combustion is called super charging is provided for super
charging.
3.3.2 Turbo super charger: Super charging is done in WDM-2 LOCO by turbo super
charger. This was discovered by German engineer altered bushy turbo super charger is
attached with engine block. During the exhaust stroke exhaust gasses are discharged in

16. 16
exhaust manifold goes to TSC gas inlet casing. Exhaust gases get direction with the help of
dome and nozzle ring and hit the turbine starts rotating at the same time blower also starts
rotating since on the common shaft thus partial vacuum is created in blower casing, hence
atmosphere air filter and destroy vacuum blower casing. Blower press the air into after cooler
where it gets cooled with water hence its density and amount of oxygen is increased the other
end of after cooler is connected to 'v' gallery and pressurized air in it. It’s called booster air
pressure booster air pressure gauge is provided in loco pilot cab to check BAP in 'v' gallery.
Maximum BAP is 1.7 kg cm.at the time of suction stroke in each cylinder super charged
airgoes into cylinder through inlet elbow and super charged the engine.
The parts of turbo super charged: -
1. Rotor assembly
2. Nozzle ring
3. Gas inlet casing
4. Turbine casing
5. Intermediate casing
6. Blower casing
7. Turbine bearing
8. Blower bearing.
Figure 3.4 Turbo super charger
3.3.3 Run down test of turbo supercharger
Aim: TO TEST THE WORKING CAPACITY.
Reason: (i) thick black smoke coming through chimney.
(ii) insufficient quantity of booster air pressure.
(iii) poor hauling power7
Precaution: (i) locomotive shouldn’t stopped under O.H.E. if the loco is stopped in the OHE
section , make sure that OHE is grounded.
Procedure:
(1) keep the engine at the idle condition for 5 mins.
(2) ensure the water temp. should be 60-65 'C
(3) stop the engine with the help of OSTA.
(4) note the time in seconds of fast coupling to stop.

17. 17
(5) hold the 'L' shaped paper on the chimney, mount and with the help of torch, note the time
in second of turbine to stop
Result: if the duration of time between stopping of fast coupling and turbine 90-180 sec, the
TSC performance is good.
3.4 FUEL OIL SYSTEM
All locomotive have individual fuel oil system. The fuel oil system is designed to introduce
fuel oil into the engine cylinders at the correct time, at correct pressure, at correct quantity
and correctly atomised. The system injects into the cylinder correctly metered amount of fuel
in highly atomised form. High pressure of fuel is required to lift the nozzle valve and for
better penetration of fuel into the combustion chamber. High pressure also helps in proper
atomisation so that the small droplets come in better contact with the compressed air in the
combustion chamber, resulting in better combustion. Metering of fuel quantity is important
because the locomotive engine is a variable speed and variable load engine with variable
requirement of fuel. Time of fuel injection is also important for better combustion.
Figure 3.5 Fuel Injector

18. 18
3.4.1 Fuel oil system
The fuel oil system consists of two integrated systems. These are-
 FUEL INJECTION PUMP (F.I.P).
 FUEL INJECTION SYSTEM.
3.4.2 Fuel injection pump
It is a constant stroke plunger type pump with variable quantity of fuel delivery to suit the
demands of the engine. The fuel cam controls the pumping stroke of the plunger. The length
of the stroke of the plunger and the time of the stroke is dependent on the cam angle and cam
profile, and the plunger spring controls the return stroke of the plunger. The plunger moves
inside the barrel, which has very close tolerances with the plunger. When the plunger reaches
to the BDC, spill ports in the barrel, which are connected to the fuel feed system, open up. Oil
then fills up the empty space inside the barrel. At the correct time in the diesel cycle, the fuel
cam pushes the plunger forward, and the moving plunger covers the spill ports. Thus, the oil
trapped in the barrel is forced out through the delivery valve to be injected into the
combustion chamber through the injection nozzle. The plunger has two identical helical
grooves or helix cut at the top edge with the relief slot. At the bottom of the plunger, there is
a lug to fit into the slot of the control sleeve. When the rotation of the engine moves the
camshaft, the fuel cam moves the plunger to make the upward stroke.
Figure 3.6 Diagram depicting fuel injection pump

19. 19
It may also rotate slightly, if necessary through the engine governor, control shaft, control
rack, and control sleeve. This rotary movement of the plunger along with reciprocating stroke
changes the position of the helical relief in respect to the spill port and oil, instead of being
delivered through the pump outlet, escapes back to the low pressure feed system. The
governor for engine speed control, on sensing the requirement of fuel, controls the rotary
motion of the plunger, while it also has reciprocating pumping strokes. Thus, the alignment
of helix relief with the spill ports will determine the effectiveness of the stroke. If the helix is
constantly in alignment with the spill ports, it bypasses the entire amount of oil, and nothing
is delivered by the pump.
The engine stops because of no fuel injected, and this is known as ‘NO-FUEL’ position.
When alignment of helix relief with spill port is delayed, it results in a partly effective stroke
and engine runs at low speed and power output is not the maximum. When the helix is not in
alignment with the spill port through out the stroke, this is known as ‘FULL FUEL
POSITION’, because the entire stroke is effective.
Oil is then passed through the delivery valve, which is spring loaded. It opens at the oil
pressure developed by the pump plunger. This helps in increasing the delivery pressure of oil.
It functions as a non-return valve, retaining oil in the high pressure line. This also helps in
snap termination of fuel injection, to arrest the tendency of dribbling during the fuel injection.
The specially designed delivery valve opens up due to the pressure built up by the pumping
stroke of plunger. When the oil pressure drops inside the barrel, the landing on the valve
moves backward to increase the space available in the high-pressure line. Thus, the pressure
inside the high-pressure line collapses, helping in snap termination of fuel injection. This
reduces the chances of dribbling at the beginning or end of fuel injection through the fuel
injection nozzles.
3.4.3 Fuel injection nozzle
The fuel injection nozzle or the fuel injector is fitted in the cylinder head with its tip projected
inside the combustion chamber. It remains connected to the respective fuel injection pump
with a steel tube known as fuel high pressure line. The fuel injection nozzle is of multi-hole
needle valve type operating against spring tension. The needle valve closes the oil holes by
blocking the oil holes due to spring pressure. Proper angle on the valve and the valve seat,
and perfect bearing ensures proper closing of the valve.

20. 20
Due to the delivery stroke of the fuel injection pump, pressure of fuel oil in the fuel duct and
the pressure chamber inside the nozzle increases. When the pressure of oil is higher than the
valve spring pressure, valve moves away from its seat, which uncovers the small holes in the
nozzle tip. High-pressure oil is then injected into the combustion chamber through these holes
in a highly atomised form. Due to injection, hydraulic pressure drops, and the valve returns
back to its seat terminating the fuel injection, termination of fuel injection may also be due to
the bypassing of fuel injection through the helix in the fuel injection pump causing a sudden
drop in pressure.
3.4.4 Calibration of fuel injection pumps
Each fuel injection pump is subject to test and calibration after repair or overhaul to ensure
that they deliver the same and stipulated amount of fuel at a particular rack position. Every
pump must deliver regulated and equal quantity of fuel at the same time so that the engine
output is optimum and at the same time running is smooth with minimum vibration.
The calibration and testing of fuel pumps are done on a specially designed machine. The
machine has a 5 HP reversible motor to drive a cam shaft through V belt. The blended test
oil of recommended viscosity under controlled temperature is circulated through a pump at
a specified pressure for feeding the pump under test. It is very much necessary to follow the
laid down standard procedure of testing to obtain standard test results. The pump under test is
fixed on top of the cam box and its rack set at a particular position to find out the quantum of
fuel delivery at that position. The machine is then switched on and the cam starts making
delivery strokes. A revolution counter attached to it is set to trip at 500 RPM or 100 RPM as
required. With the cam making strokes, if the pump delivers any oil, it returns back to the
reservoir in normal state. A manually operated solenoid switch is switched on and the oil is
diverted to a measure glass till 300 strokes are completed after operation of the solenoid
switch. Thus the oil discharged at 300 working strokes of the pump is measured which
should normally be within the stipulated limit. The purpose of measuring the output in 300
strokes is to take an average to avoid errors. The pump is tested at idling and full fuel
positions to make sure that they deliver the correct amount of fuel for maintaining the idling
speed and so also deliver full HP at full load. A counter check of the result at idling is done
on the reverse position of the motor which simulates slow running of the engine.

21. 21
If the test results are not within the stipulated limits as indicated by the makers then
adjustment of the fuel rack position may be required by moving the rack pointer, by addition
or removal of shims behind it. The thickness of shims used should be punched on the pump
body. The adjustment of rack is done at the full fuel position to ensure that the engine would
deliver full horse power. Once the adjustment is done at full fuel position other adjustment
should come automatically. In the event of inconsistency in results between full fuel and
idling fuel, it may call for change of plunger and barrel assembly.
3.4.5 Spray pattern
Spray of fuel should take place through all the holes uniformly and properly atomized.
While the atomization can be seen through the glass jar, an impression taken on a sheet of
blotting paper at a distance of 1 to 1 1/2 inch also gives a clear impression of the spray
pattern.
3.4.6 Spray pressure
The stipulated correct pressure at which the spray should take place 3900-4050 psi for
new and 3700-3800 psi for re-conditioned nozzles. If the pressure is down to 3600 psi the
nozzle needs replacement. The spray pressure is indicated in the gauge provided in the test
machine. Shims are being used to increase or decrease the tension of nozzle spring which
increases or decreases the spray pressure.
3.5 EXPRESSOR
In Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air
brakes. As such provision has been made on every diesel loco for both vacuum and
compressed air for operation of the system as a combination brake system for simultaneous
application on locomotive and train.

22. 22
_______________________________________
Figure 3.7 Expressor
In ALCO locos the exhauster and the compressor are combined into one unit and it is known
as EXPRESSOR. It creates 23" of vacuum in the train pipe and 140 PSI air pressure in the
reservoir for operating the brake system and use in the control system etc. The expressor is
locatedat the free end of the engine block and driven through the extension shaft attached to the
engine crankshaft.The twoare coupledtogetherbyfastcoupling(Kopper'scoupling). Naturally the
expressorcrankshafthaseightspeedslike the engine crankshaft. There are two types of expressor
are, 6CD,4UC & 6CD,3UC. In 6CD,4UC expressor there are six cylinder and four exhausters whereas
6CD,3UC contain six cylinder and three exhausters.
3.5.1 Working of exhauster
Air from vacuum train pipe is drawn into the exhauster cylinders through the open inlet
valves in the cylinder heads during its suction stroke. Each of the exhauster cylinders has one
or two inlet valves and two discharge valves in the cylinder head. A study of the inlet and
discharge valves as given in a separate diagram would indicate that individual components
like (1) plate valve outer (2) plate valve inner (3) spring outer (4) spring inner etc. are all
interchangeable parts. Only basic difference is that they are arranged in the reverse manner
in the valve assemblies which may also have different size and shape. The retainer stud in

23. 23
both the assemblies must project upward to avoid hitting the piston. The pressure differential
betweenthe availablepressureinthe vacuumtrainpipe andinside the exhaustercylinderopensthe
inletvalve andairisdrawn intothe cylinderfromtrainpipe duringsuction stroke. Inthe next stroke
of the pistonthe airis compressedandforcedoutthrough the discharge valve while the inlet valve
remainsclosed. The differential airpressure also automatically open or close the discharge valves,
the same way as the inletvalvesoperate. Thisprocessof suctionof airfrom the trainpipe continues
to create requiredamount of vacuum and discharge the same air to atmosphere. The VA-1 control
valve helpsinmaintainingthe vacuumtorequisitelevel despite continuedworkingof the exhauster.
3.5.2 Compressor
The compressor is a two stage compressor with one low pressure cylinder and one high
pressure cylinder. During the first stage of compression it is done in the low pressure
cylinder where suction is through a wire mesh filter. After compression in the LP cylinder
air is delivered into the discharge manifold at a pressure of 30 / 35 PSI. Workings of the inlet
and exhaust valves are similar to that of exhauster which automatically open or close under
differential air pressure. For inter-cooling air is then passed through a radiator known as
inter-cooler. This is an air to air cooler where compressed air passes through the element
tubes and cool atmospheric air is blown on the outside fins by a fan fitted on the expressor
crank shaft. Cooling of air at this stage increases the volumetric efficiency of air before it
enters the high- pressure cylinder. A safety valve known as inter cooler safety valve set at 60
PSI is provided after the inter cooler as a protection against high pressure developing in the
after cooler due to defect of valves.
After the first stage of compression and after-cooling the air is again compressed in a
cylinder of smaller diameter to increase the pressure to 135-140 PSI in the same way. This is
the second stage of compression in the HP cylinder. Air again needs cooling before it is
finally sent to the air reservoir and this is done while the air passes through a set of coiled
tubes after cooler.
3.6 AIR BRAKES
An air brake is a conveyance braking system actuated by compressed air. Modern trains rely
upon a fail preventive air brake system that is based upon a design patented by George
Westinghouse on March 5,1872. In the air brake's simplest form, called the straight air

24. 24
system, compressed air pushes on a piston in a cylinder. The piston is connected through
mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction
to slow the train.
Figure 3.8 Air brake controller
3.6.1 Air brake system operation
The compressor in the locomotive produces the air supplied to the system. It is stored in
the main reservoir. Regulated pressure of 6 kg/cm2 flows to the feed pipe through feed valve
and 5-kg/cm2 pressure by driver’s brake valve to the brake pipe. The feed pipe through check
valve charges air reservoir via isolating cock and also by brake pipe through distributor valve.
The brake pipe pressure controls the distributor valves of all the coaches/wagons which in

25. 25
turn control the flow of compressed air from Air reservoir to break cylinder in application
and from brake cylinder to atmosphere in release.
During application, the driver in the loco lowers the BP pressure. This brake pipe pressure
reduction causes opening of brake cylinder inlet passage and simultaneously closing of brake
cylinder outlet passage of the distributor valve. In this situation, auxiliary reservoir supplies
air to brake cylinder. At application time, pressure in the brake cylinder and other brake
characteristics are controlled by distributor valve.
During release, the BP pressure is raised to 5 kg/cm2 . This brake pipe pressure causes closing
of brake cylinder inlet passage and simultaneously opening of brake cylinder outlet passage
of the distributor valve.
Layout-
Figure 3.9 Layout of braking system
PEV
ARCR
DV
DC
BC BC
DC
PEASD PEASD
FP
BP
GEBV
Pressure
gauge
Cut off
angle cock
Passenger alarm
system
Guard
emergency
brake
system
Core
brake
system

26. 26
3.7 ALTERNATOR
This is an electric machine which converts the mechanical energy into electrical energy and
produces the AC current. The alternator is also likewise DC generator and works on the
fundamental principal of magnetic induction. This has the following advantages:
1. As such there is no commutator in the alternator hence the defects which arises
through commutator does not happen in these types of loco.
2. Negligiblle possibilities of power ground due to non provision of commutator at
carbon brushes.
3. As such there are two slip rings and two carbon brush holder., hence easy to maintain.
4. The NLV (no load voltage) of AC traction is 980 volt whereas on the other locos it is
set at 1100 volt.
5. The rotor of the AC traction generator is rotated with the diesel engine crank shaft and
the electricity produced is also absorbed through 3 phase stator winding. This electric
power is transformed through power diode in the rectifier panel into DC then is given
to traction motors. Hence due to this process the rectifier panel becomes very hot so
cool down the rectifier panel. The traction motor blower pressurized air used. This air
is also used to cool down the exciter and auxiliary generator.
Figure 3.10 Alternator

27. 27
3.8 GENERATOR
The generator is the machine which converts mechanical energy into electrical energy which
is based on the principal of electromagnetic induction. It produces the high voltage which is
used to revolve the traction motor.
3.8.1 Voltage of main generator
HGMG 120-680
HEAZ 120-750
GE 120-780
First of all the main generator is rotated with the help of battery current, before the engine is
started. As soon as the crankshaft is rotated and completes the four cycle of the strikes then
the crankshaft gives the drive to the armature of the main generator.
One flywheel is fitted with the main generator. This wheel sucks the atmospheric air and
cools the main generator. This main generator has one armature. Armature is equipped with
carbon brushes. And the carbon brushes are fitted with brush holder.
GE = 12 holder X 6 carbon brush = 72 carbon brush
HE = 10 holder X 6 carbon brush = 60 carbon brush
3.8.2 Main generator has three fileds:
1. Starting field
2. Shunt filed
3. Commutating field
3.8.3 Auxiliary generator
It is a gear driven from main generator bull gear four pole and commutative pole, shunt
wound DC generator which supplies current for battery charging on locomotive as well as
auxiliaries such as crankcase exhauster motor (CCEM), FPM, ECC coil assembly, relays and
light circuits. It produces constant voltage irrespective of notches.

28. 28
General data
Working voltage= 74 volts
Maximum current = 160 Amp.
Maximum speed= 954 - 2386 rpm
No. of brush arms= 4
No. of brush holders= 4
3.8.4 Exciter generator
It is also gear driven from main generator and is 3 phase separately excited ac machine. The
rotating field is excited from the batteries through slip rings and carbon brushes. It provide
current for exciting the main generator filed through generator field contactor
(gf) and also supplies current to governor speed coil through rp ( rectifier panel) and ecp.
One type locomotive dc exciter supplies current for excitation of main generator field.
Generator speed coils gets the current from tacho generator. The dc exciter one type
locomotive is same as auxiliary generator.
3.8.5 Tacho generator
This is 3 phase ac generator driven by cam shaft gear and produces the signal proportional to
diesel engine speed it controls the engine speed output of the machine is used to control horse
power limit in every notch. If there is loose connection, then the defect will arise in the speed
circuit and engine will shut down with over speed.
3.8.6 Axle generator
This is simple phase ac generator having temporary magnet and fitted on loco left side wheel
no. 2 axle box. When the wheel rotates it produces the current to the tune of 125 volts. Axle

29. 29
generator gives current to the transition circuit and different transition takes place. Apart from
this it also gives to the electrical speedometer. Hence if axle generator is defective neither
electric speedometer will work nor transition takes place.
3.9 CYLINDER HEAD
The cylinder head is held on to the cylinder liner by seven hold down studs or bolts provided
on the cylinder block. It is subjected to high shock stress and combustion temperature at the
lower face, which forms a part of combustion chamber. It is a complicated casting where
cooling passages are cored for holding water for cooling the cylinder head. In addition to this
provision is made for providing passage of inlet air and exhaust gas. Further, space has been
provided for holding fuel injection nozzles, valve guides and valve seat inserts also.
Figure 3.11 Cylinder head

30. 30
3.9.1 Components of cylinder head
In cylinder heads valve seat inserts with lock rings are used as replaceable wearing part. The
inserts are made of stellite or weltite. To provide interference fit, inserts are frozen in ice and
cylinder head is heated to bring about a temperature differential of 250F and the insert is
pushed into recess in cylinder head. The valve seat inserts are ground to an angle of 44.5
whereas the valve is ground to 45 to ensure line contact. (In the latest engines the inlet
valves are ground at 30° and seats are ground at 29.5°). Each cylinder has 2 exhaust and 2
inlet valves of 2.85" in dia. The valves have stem of alloy steel and valve head of austenitic
stainless steel, butt-welded together into a composite unit. The valve head material being
austenitic steel has high level of stretch resistance and is capable of hardening above
Rockwell- 34 to resist deformation due to continuous pounding action.
The valve guides are interference fit to the cylinder head with an interference of 0.0008" to
0.0018". After attention to the cylinder heads the same is hydraulically tested at 70 psi and
190F. The fitment of cylinder heads is done in ALCO engines with a torque value of 550
Ft.lbs. The cylinder head is a metal-to-metal joint on to cylinder.
ALCO 251+ cylinder heads are the latest generation cylinder heads, used in updated engines,
with the following feature:
 Fire deck thickness reduced for better heat transmission.
 Middle deck modified by increasing number of ribs (supports) to increase its mechanical
strength. The flying buttress fashion of middle deck improves the flow pattern of water
eliminating water stagnation at the corners inside cylinder head.
 Water holding capacity increased by increasing number of cores (14 instead of 11)
 Use of frost core plugs instead of threaded plugs, arrest tendency of leakage.
 Made lighter by 8 kgs (Al spacer is used to make good the gap between rubber grommet
and cylinder head.)
 Retaining rings of valve seat inserts eliminated.
3.9.2 Benefits:-
 Better heat dissipation
 Failure reduced by reducing crack and eliminating sagging effect of fire deck area.

31. 31
3.9.3 Maintenance and Inspection
Cleaning:
By dipping in a tank containing caustic solution or ORION-355 solution with water (1:5)
supported by air agitation and heating.
Crack Inspection:
Check face cracks and inserts cracks by dye penetration test.
Hydraulic Test:
Conduct hyd. test (at 70 psi, 200°F for 30 min.) for checking water leakage at nozzle sleeve,
ferrule, core plugs and combustion face.
Dimensional check:
Face seat thickness: within 0.005" to 0.020"
Straightness of valve stem: Run out should not exceed 0.0005"
Free & Compressed height (at 118 lbs.) of springs: 3 13/16" & 4 13/16"
Checks during overhauling:
Ground the valve seat insert to 44.5°/29.5°, maintain run out of insert within 0.002" with
respect to valve guide while grinding.
Grind the valves to 45°/30° and ensure continuous hair line contact with valve guide by
checking colour match.
Ensure no crack has developed to inserts after grinding, checked by dye penetration test.
Make pairing of springs and check proper draw on valve locks and proper condition of
groove and locks while assembling of valves.
Lap the face joint to ensure leak proof joint with liner.

32. 32
Blow by test:
On bench blow by test is conducted to ensure the sealing effect of cylinder head.
Blow by test is also conducted to check the sealing efficiency of the combustion chamber on
a running engine, as per the following procedure:
 Run the engine to attain normal operating temperature (65°C)
 Stop running after attaining normal operating temperature.
 Bring the piston of the corresponding cylinder at TDC in compression stroke.
 Fit blow-by gadget (Consists of compressed air line with the provision of a pressure
gauge and stopcock) removing decompression plug.
 Charge the combustion chamber with compressed air.
 Cut off air supply at 70 psi. Through stop cock and record the time when it comes down
to zero.7 to 10 secs is OK.

33. 33
CHAPTER-4
DIFFERENT SYSTEMS IN LOCOMOTIVES
4.1 FUEL OIL SYSTEM: The fuel oil system is designed to introduce fuel oil into the
engines cylinders at the correct time, at correct high-pressure, at correct quantity and correct
atomized. To create power in the locomotive engine high speed diesel oil is used. The
purpose of the fuel oil system is to suck the fuel oil from the tank against gravitational force,
filter it and supply to cylinder with adequate pressure.
4.1.1 Description: A fuel oil tank is provided in between two bogeys of
under track. Its capacity is 500 liters, fuel used in the system is HSD (high speed diesel). Two
vent pipe are provided on tank to evacuate the gases. One drain plug is provided at the
bottom of the tank. There are two glows rod gauges on both side of loco to check fuel oil
balance in the tank, glow rod having marking from 540 to n5000 litres. Each dot shows 25
litre .fail the loco when oil level is less than 540 liters.
Fuel pump motor is fitted on engine right side in compressor room. Its
horse power is 1 on other side of FPM, fuel pump (engine room side) and governor (radiator
room side)is provided. Initially it is started by battery, after starting engine it is run by
auxiliary generator, necessary circuit engine it is run by auxiliary generator. Necessary circuit
breaker is required to close for starting the fuel pump motor. When fuel oil pump is starts, it
sucks fuel oil from the tank through cage(TRAP)strainer and goes to delivery pipe. Relief
valve is set at 5kg/cm2 is connected on it to ensure the safety of fuel pump from over loading
by-passes the excess fuel to the tank, then fuel oil goes to the primary filter and secondary
filter. Both filter are provided in engine right side free end near cylinder no 1
The purified fuel goes through the right side fuel oil gallery then cross over
pipe to left side fuel oil gallery. One copper pipe connection given to regularity valve (setting
4kg/cm2) and fuel oil pressure gauge. From both side gallery fuel is supplied to FIP with the
help of jump pipes. Flip is a reciprocation pump operated by cam shaft. The flip converts the
furl oil pressure up to 3900-4050psc and send to the fuel injector through a high pressure
pipe. FIP is connected to fuel rake having marking from 0 to 309 m on requirement. FIP can
be dummied with the help of lock device.

34. 34
Fuel injector is fitted in the cylinder head. It has a nozzle having fine a holes. It the end of
compression store the fuel oil is injected in the end of compression stroke the fuel oil is
injected in atomized into the cylinder to get power stroke.
4.1.2 Parts of fuel oil system:
(1) fuel oil tank (2) fuel oil filling strainer.
(3) glow rod gauge (4) drain plug
(5) primary filter (6) fuel transfer pump
(7) secondary filter (8) fuel oil relief valve
(9) right side fuel gallery (10) benzo pipe & benzo bolt
(11) fuel injection pump (12) fuel injector
(13) high pressure pipe (14) flexible cross over pipe
(15) left fuel oil gallery (16) fuel oil gallery
(17) fuel oil regulating valve (18) fuel oil pressure gauge
(19) fuel oil return pipe (20) fuel oil return gallery
Fuel oil pressure not build up:
There are mainly two reasons for not build up the fuel oil pressure.
(a) electrical cause
(b) mechanical cause
Figure 4.1 Layout showing Fuel supply system

35. 35
4.2 WATER COOLING SYSTEM:
The purpose of cooling water system is to cool engine equipment as well as
(1) to cool the engine block
(2) to cool the inlet air
(3) to cool the lube oil
(4) to cool TSC
4.2.1 The main parts of water cooling system:
(1) water pump (2) eddy current clutch
(3) radiator (4) radiator fan
(5) jumper pipe + radiator pipe (6) low water switch (LWS)
(7) water pipe+ return pipe (8) water temperature gauge
(9) ETS- 1,2,3
4.2.2 Description: Chemical treated water is filled on water cooling system due to chemical
treated water compression scaling will not formed and also leakages will visible easily.
On wdm2 loco pressurized water cooling system is provided for cooling. For the purpose
one centrifugal water pump is provided on left side free end of the engine which gets drive
from extension shaft gear (9r46:79). In the system there is ers of water filled through
expansion tank no1 situated on top of the radiator room.
When the diesel engine starts, water pump suck water from radiator core through suction
pipe of expansion tank no1 sent to TSC water pipe, right side radiator core, left side radiator
core through lube oil cooler. From here the water is pumped in four places.
(1) right side engine block
(2) left side engine block
(3) TSC
(4) after cooling
Discussed above points one by one below:
(1) & (2) right/ left side engine block:
the water going to right/left side engine block, cool the cylinder liner and after that rises
through jumper pipe to each cylinder head and cools the cylinder head and rises through riser
pipe to the respective water return pipe i.e. Right side water return pipe & left side water

36. 36
return pipe. Right side water return pipe water goes to the left side side radiator core through
bubble collector and left side water returns pipe goes to right side radiator core through
bubble collector. In the radiator core water gets cooled by working of radiator fan electricity.
After getting cold left side radiator core water goes to lube oil cooler, where it cools lube oil
and comes out and mixes with water of right side radiator core and goes to the water pump
again.
(3) TSC (turbo super charger): The second connection goes to TSC. This connection to
intermediate casing at the bottom of TSC with the help of flexible pipe. From here water goes
to turbine casing for cooling. After cooling turbine casing water comes out from three
(a) steam accumulator goes to water pump suction pipe.
(b) second pipe from steam accumulator goes to expansion tank NO1.
(c) right side outlet pipe of turbine casing also goes to expansion tank NO1 & left side out let
is connected to the after cooler outlet pipe.
(4) After cooler:
The third connection goes to after cooler where it cools air for v-gallery and further water
will go left side engine block.
In radiator room water is cooled by radiator fan, which works according to the water temp.
This water temp. Is measured by three thermostatic switches i.e. ETS1-64'c , ETS2-68'c,
ETC3-90'c. These engine temp. Switches are located in expressor room water junction box.
ETS-1 64'c- slow working
ETS-2-68'c- full speed
ETS-3-90'c- hot engine, alarm indication & buzzer.
When the water level of the tank is 1" from the tank the LWS will operate and engine will
shut down automatically with hot engine indication and buzzer.

37. 37
Figure 4.2 Layout of the water supply system
4.3 LUBE OIL SYSTEM:
Each and every machine parts when rubbed with each other , produces heat. Due to heat it
may damage the parts . Hence long life of parts lubricating system is used.
For this reason lube oil is used in diesel loco.
4.3.1 Parts of lube oil system:
1) suction pipe 2) lube oil pump
3) pump outlet pipe 4) pressure relief valve
5) bye pass valve 6) lube oil filter housing(8 filter)
7) filter drain cock 8) lube oil cooler or heat exchanger
9) regulating valve. 10) lube oil strainer & its drain cock
11) main header 12) right sub header
13) left sub header 14) TSC

38. 38
15) ops 16) driver cabin gauge
17) extension shaft gear 18) cylinder head
19) O.S.T carrer 20) cam shaft
21) vibration damper 22) cam shaft gear
23) fuel injection pump cross head.
4.3.2 Description: Forced lubrication system is used in deisel loco motive. The detail of
system is as lower portion of engine crank case. It is used as lube oil sump. Its capacity is 910
liters to fill the lube oil filling cap is provided on free end engine right side. Dip stick gauge is
provided 0-400 litres marking and each mark of 20 ltr. While checking lube oil level engine
should be on idle condition and crank case exhauster motor should be in 'on' position and
engraved loco number on the dip stick.
Lube oil pump is positive 'displacement type' and located in engine room right side free end.
It gets drive from main crank shaft extension shaft no1 gear of 79 teeths matching with pump
gear is having 67 teeths. When diesel engine starts, lube oil pump also starts working .it sucks
oil from the sump and sends to delivery pipe. On delivery pipe a releif valve (setting 9.0
kg/cm'') is provided.oil from delivery pipe goes to filter drum . It has two zones, unfilterd
zone having 8 paper type filter, this zone cover is tied with 8 wings nut. From this zone
filtered oil will go to filter zone. Each zone having seperate drain cock. It should be tight and
sealed. One bye pass valve (setting 20 psi diff. Pressure) is provided near filter drum at
engine starting time or when filters chocked up.
Filter oil from lube oil filter drum goes to lube oil cooler.it is located in radiator room. Here
oil gets cool with water tubes, out going pipe of lube cooler having regulating valve (setting
6.0 kg/cm''). Before this valve one connection given to tsc through micro filter to lubricate
bearing in intermediate casing.
The oil coming from lube cooler goes to lube oil strainer(engine room left side). Strainer
having one drain cock. It should be tight and sealed. After filtering oil goes to main header
(location lube oil sump). Main header having 9 jumper pipe and each pipe is connected to
main bearing. After lubrication the connecting rod bearing. From connecting rod oil goes to
piston pin and lubricate it and also cool the piston crown. Further , oil dropped in the sump
through return pipe, while droping oil splash and lubricated the cylinder liners.
Two pipe connection were given from main header to sub header and one t joint on each pipe
given for cam shaft, which helps in lubricating cam shaft bearings.from both sub header two

39. 39
pipe connection are provided for each cylinder to lubricate rocker arm assembly & fuel pump
filter at the end of both sub header on power take off end, one nozzle is provided to lubricate
cam shaft gear as well as split gear in spray form.
From main bearing no1 oil goes to vibration damper, it reduces the main crank shaft
vibration.
From main header one connection given to lube oil pressure gauge and oil pressure switch in
loco pilot cab.
Figure 4.3 Layout showing lube oil system
4.4 BRAKE SYSTEM:
4.4.1 Vacuum brake system:
Most of the WDM2 locomotives are based on vacuum brakes system which is called 28
LV-1 brake system. In this system loco brake can be applied independently and with train
brake also. If loco brakes are applied with train brake is called synchronized system. In this

40. 40
system on the multiple locos the loco break can be applied to rear locomotives from the front
locomotive. To apply the break, pressurised air is applied. This compressed air is developed
in the expressor or compressor and is filled in MR1 & MR2 and onwords is being supplied to
different brake valves.
4.4.2 The valve and other equipments used in 28lv-1 brake system:
(1) A9 automatic brake valve (2) SA9 independent brake valve
(3) MU-2B valve (4) HS4 valve
(5) BA-1 control valve (6) HB-5 relay valve
(7) H-5 relay valve (8) F-1 selector
(9) C-2 relay valve (10) 28 VB control valve
(11) A-1 differential pilot valve (12) BA-1 release valve
(13) D1 pilot valve (14) vacuum check valve.
Figure 4.4 Layout of synchronization of brakes and quick release

41. 41
Method of creating vacuum:
To create vacuum in the train pipe MR2 pressure is sent at all these places
(1) A9 BRAKE (2) H.S4 VALVE VALVE
(1) A9 brake valve:
The MR pressure in A9 valve is adjusted with the A-9 adjusting coc in the control
stand to 5 kgcm'' and is called brake pipe pressure. When this brake pipe pressure is adjusted
& being the MU2B valve in lead position, it goes on the diaphragm of VA1b control valve
through equalizing pipe, working control stand A9 coc/direction coc in open condition.
The pressure which was (HS4 valve) adjusted to 1.7 kgcm'' is sent at the bottom
diaphragm of VA-1 control valve. In this way the pressure of the top & button keeps the
spool valve.
In the balance position. In this condition the passage/ channel has direct connection of
vacuum train pipe and exhauster of the expressor and train pipe air through exhausted and
specified amount of vacuum is created in the vacuum train pipe.
When A-9 valve is brought to application then vacuum brake is applied because decreasing
the pressure through A-9 valve over the VAIB control valve allows the spool valve to lift
upward and the channel or passage between exhauster and train pipe and train vacuum brake
are applied. The working control stand of coc A-9 should be opened and other.
Dual brake loco:
This method is called 28 LAV-1 system. The MR pressure of 9 kg/cm'' in the system, stops
behind the following valves.
(1) on A9 valve of both control stand.
(2) on MU2B valve.
(3) on additional C-2 relay valve
(4) on HS4 control valve
(5) on c2 relay valve.
(6) on VA-1 release valve.
When the A9 handle is kept on release positive then MR pressure of 5 kg/cm'' after adjusting
with A9 cock and provided the A9 direction cock in open position reach at MU2B valve, if
the MU2B valve is in release position it reaches the additional C2 relay valve and open ates
the add. C2 relay valve. Now the MR2 pressure which was standing at the odd c2 relay valve
is reduced to 5.